Remote center of motion control for a surgical robot

ABSTRACT

For control about a remote center of motion (RCM) of a surgical robotic system, possible configurations of a robotic manipulator are searched to find the configuration providing a greatest overlap of the workspace of the surgical instrument with the target anatomy. The force at the RCM may be measured, such as with one or more sensors on the cannula or in an adaptor connecting the robotic manipulator to the cannula. The measured force is used to determine a change in the RCM to minimize the force exerted on the patient at the RCM. Given this change, the configuration of the robotic manipulator may be dynamically updated. Various aspects of this RCM control may be used alone or in combination, such as to optimize the alignment of workspace to the target anatomy, to minimize force at the RCM, and/or to dynamically control the robotic manipulator configuration based on workspace alignment and force measurement.

BACKGROUND

The present embodiments relate to robotic systems for minimally invasivesurgery (MIS). MIS may be performed with robotic systems that includeone or more robotic manipulators for manipulating surgical tools basedon commands from a remote operator. A robotic manipulator may, forexample, support at its distal end various surgical instruments anddevices, including scalpels, clamps, scissors, and imaging devices(e.g., endoscope). Using the robotic system, the surgeon controls therobotic manipulators in teleoperation during MIS.

The surgical instruments and devices are inserted into the body of thepatient via cannulas. By hardware or software design, the roboticmanipulator has a remote center of motion (RCM) that is stationaryrelative to the base of the robotic manipulator and thus to the patient.To avoid injury to the patient, the RCM is aligned with the insertionpoint on the cannula. The robotic manipulator has a confined workspace,which describes the patient volume inside which the surgical instrumenttip can reach and operate. Using a redundant robotic manipulator (e.g.,more than 6 joints), there exist several different configurations inwhich the robotic manipulator can be docked to a cannula. As theconfiguration of the robot arm changes while maintaining the RCM, theworkspace also moves. Among these configurations, one may be preferableover the others to ensure that most or all of the target anatomy fallswithin the operable workspace. Unnecessary trauma may be caused to apatient should it be discovered after cannula placement that theinstrument does not reach the target anatomy. It is important to bringthe robotic manipulator(s) to a proper configuration where the targetanatomy is within reach of the surgical instrument in the shortestpossible time and not extend the patient's time under anesthesia.

Once docked to the cannula, the robotic manipulator is not necessarilyat an “optimal” configuration ensuring that the target anatomy is in itsworkspace. The “non-optimal” configuration of the robotic manipulatorrelative to the target anatomy may be due to the docking process. Thetarget anatomy may also be redefined during the operation. Under thesecircumstances, the robotic manipulator may need to be reconfigured toalign the workspace with the target anatomy. The reconfiguration may beby moving various joints of the manipulator around the fixed insertionport to coincide the workspace with the target anatomy. Manuallyreconfiguring (1) takes significant mental effort to visualize the shapeand motion of the workspace as the arms are moved and (2) takes physicaleffort as multiple joints of the robotic manipulator may need to bemoved one-by-one. Multiple adjustments may be needed due to complexmechanical structure before reaching the desired configuration, all ofwhich expend valuable intraoperative time. In a complex robotic systemwith several degrees of freedom, it is difficult to visualize theworkspace of the robot, especially exactly how the configurationdetermines the workspace.

SUMMARY

By way of introduction, the preferred embodiments described belowinclude methods, systems, instructions, and computer readable media forRCM control of a surgical robotic system. Given an RCM, possibleconfigurations of a robotic manipulator are searched to find theconfiguration providing a greatest overlap of the workspace of thesurgical instrument with the target anatomy. The force at the RCM may bemeasured, such as with one or more sensors on the cannula or in anadaptor connecting the robotic manipulator to the cannula. The measuredforce is used to determine a change in the RCM to minimize the forceexerted on the patient at the RCM. Given this change, the configurationof the robotic manipulator may be dynamically updated. Various aspectsof this RCM control may be used alone or in combination, such as tooptimize the alignment of workspace to the target anatomy, to minimizeforce at the RCM, and/or to dynamically control the robotic manipulatorconfiguration based on workspace alignment and force measurement.

In a first aspect, a method is provided for RCM control of a surgicalrobotic system. An RCM is established for a robotic manipulator. Anamount of overlap between a target anatomy and each of a plurality ofworkspaces of a surgical instrument on the robotic manipulator isdetermined. The workspaces correspond to different configurations of therobotic manipulator about the RCM. The configuration of the roboticmanipulator with a greatest of the amount of overlap is selected. Therobotic manipulator joints are moved to new positions corresponding tothe selected configuration.

In a second aspect, a method is provided for RCM control of a surgicalrobotic system. A force at the RCM is measured. The robotic manipulatorconfiguration is adjusted to reduce the force exertion at the RCM and tomaintain an overlap between the workspace of the surgical instrument anda target anatomy in the patient.

In a third aspect, a surgical robotic system is provided for medicalteleoperation. A surgical instrument connects to a robotic manipulator.An adaptor connects to the robotic manipulator. The adaptor isconfigured to connect with a cannula during teleoperation. One or moreforce sensors are on the adaptor. A controller is configured to adjust aRCM of the robotic manipulator based on output from the force sensor.

The present invention is defined by the following claims, and nothing inthis section should be taken as a limitation on those claims. Anyteaching for one type of claim (e.g., method) may be applicable toanother type of claim (e.g., computer readable storage medium orsystem). Further aspects and advantages of the invention are discussedbelow in conjunction with the preferred embodiments and may be laterclaimed independently or in combination.

BRIEF DESCRIPTION OF THE DRAWINGS

The components and the figures are not necessarily to scale, emphasisinstead being placed upon illustrating the principles of the invention.Moreover, in the figures, like reference numerals designatecorresponding parts throughout the different views.

FIG. 1 is an illustration of one embodiment of an operating roomenvironment with a surgical robotic system according to one embodiment;

FIG. 2 illustrates an example surgical robot arm and surgical tool;

FIG. 3 is a flow chart diagram of one embodiment of a method for remotecenter of motion control of a surgical robotic system;

FIGS. 4A and 4B show an example adaptor and sensor for connecting with acannula;

FIG. 5 illustrates example workspace alignment with target anatomy;

FIG. 6 illustrates example workspace alignment while also includingforce sensing at the remote center of motion; and

FIG. 7 is a block diagram of one embodiment of a surgical roboticsystem.

DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED EMBODIMENTS

Assisted arm manipulation is provided for repositioning the remotecenter of motion (RCM). The RCM may be safely, easily, and quicklyrepositioned or maintained so that the overlapping volume between thetarget anatomy and a workspace of a robotic manipulator (e.g., roboticarm) and surgical instrument is maximized. Possible robotic manipulatorconfigurations are tested to identify an optimal level of overlap givena position of the RCM. The robotic manipulator may be moved to accountfor this alignment, repositioning the RCM, and/or teleoperation.

Cannula (e.g., trocar) force (e.g., translational, pressure, and/ortorque) measurement may be used for adaptive RCM control. The RCM may bemoved to adapt to patient motion, motion of the robotic manipulator, oranother source of undesired force on the tissue of the patient at theinsertion (i.e., RCM is at the entry location into the patient). In oneembodiment, the force is measured with a sensor on the cannula. Inanother embodiment, the force exerted on the cannula is measured usingsensors at the contacting points with the adapter of the roboticmanipulator. Information about the force and stress at the cannulainsertion point through the abdomen wall is provided by the measurementsat the adaptor, assisting the user or controller to adjust the positionof the RCM accordingly and to release excessive stress on the abdomenwall as needed.

FIGS. 1 and 2 show an example surgical robotic system. The approachesfor RCM control are discussed below in reference to this example system.Other surgical robotic systems and surgical robots or non-surgicalrobotic systems and robots may use the approaches.

FIGS. 3-6 are directed to RCM control, including workspace alignmentwith the target anatomy and/or force sensing on the adaptor. FIG. 7 isdirected to a system for RCM control.

FIG. 1 is a diagram illustrating an example operating room environmentwith a surgical robotic system 100 for which commands from the user areconverted into motion of the surgical robotic manipulators 122 withiterative inverse kinematics. The surgical robotic system 100 includes auser console 110, a control tower 130, and a surgical robot 120 havingone or more surgical robotic manipulators 122 mounted on a surgicalplatform 124 (e.g., a table or a bed etc.), where surgical tools withend effectors are attached to the distal ends of the roboticmanipulators 122 for executing a surgical procedure. Additional,different, or fewer components may be provided, such as combining thecontrol tower 130 with the console 110 or surgical robot 120. Therobotic manipulators 122 are shown as table-mounted, but in otherconfigurations, the robotic manipulators 122 may be mounted in a cart, aceiling, a sidewall, or other suitable support surfaces.

Generally, a user, such as a surgeon or other operator, may be seated atthe user console 110 to remotely manipulate the robotic manipulators 122and/or surgical instruments (e.g., teleoperation). The user console 110may be located in the same operation room as the robotic system 100, asshown in FIG. 1. In other environments, the user console 110 may belocated in an adjacent or nearby room, or tele-operated from a remotelocation in a different building, city, or country. The user console 110may include a seat 112, pedals 114, one or more handheld user interfacedevices (UIDs) 116, and an open display 118 configured to display, forexample, a view of the surgical site inside a patient and graphic userinterface. As shown in the exemplary user console 110, a surgeon sittingin the seat 112 and viewing the open display 118 may manipulate thepedals 114 and/or handheld user interface devices 116 to remotely anddirectly control the robotic arms 122 and/or surgical instrumentsmounted to the distal ends of the arms 122. The user inputs commands forthe movement of the surgical manipulators 122 and/or end effectors. Thisuser control determines position, the rate of movement, and the changein rate of movement of the robotic manipulators 122. The rate and changein rate result in dynamic torque expected to be provided by the roboticmanipulators 122. The surgeon sitting in the seat 112 may view andinteract with the display 118 to input commands for movement inteleoperation of the robotic manipulators 122 and/or surgicalinstruments in the surgery.

In some variations, a user may also operate the surgical robotic system100 in an “over the bed” (OTB) mode, in which the user is at thepatient's side and simultaneously manipulating a robotically-driventool/end effector attached thereto (e.g., with a handheld user interfacedevice 116 held in one hand) and a manual laparoscopic tool. Forexample, the user's left hand may be manipulating a handheld userinterface device 116 to control a robotic surgical component while theuser's right hand may be manipulating a manual laparoscopic tool. Thus,in these variations, the user may perform both robotic-assisted MIS andmanual laparoscopic surgery on a patient.

During an exemplary procedure or surgery, the patient is prepped anddraped in a sterile fashion to achieve anesthesia. Initial access to thesurgical site may be performed manually with the robotic system 100 in astowed configuration or withdrawn configuration to facilitate access tothe surgical site. Once the access is completed, initial positioningand/or preparation of the robotic system may be performed. During theprocedure, a surgeon in the user console 110 may utilize the pedals 114and/or user interface devices 116 to manipulate various end effectorsand/or imaging systems to perform the surgery using teleoperation. Themovements may be surgeon, patient, and/or situation specific, so mayvary. Manual assistance may also be provided at the procedure table bysterile-gowned personnel, who may perform tasks including but notlimited to, retracting tissues or performing manual repositioning ortool exchange involving one or more robotic manipulators 122. Somesurgical tasks, such as retracting, suturing, or other tissuemanipulation, may instead be performed by one or more roboticmanipulators 122 (e.g., third or fourth arms). Nonsterile personnel mayalso be present to assist the surgeon at the user console 110. When theprocedure or surgery is completed, the robotic system 100 and/or userconsole 110 may be configured or set in a state to facilitate one ormore post-operative procedures, including but not limited to, roboticsystem 100 cleaning and/or sterilization, and/or healthcare record entryor printout, whether electronic or hard copy, such as via the userconsole 110.

In some aspects, the communication between the surgical robot 120 andthe user console 110 may be through the control tower 130, which maytranslate user input commands from the user console 110 to roboticcontrol commands and transmit the control commands to the surgical robot120. The control tower 130 performs iterative inverse kinematics. Thecontrol tower 130 may also transmit status and feedback from the robot120 back to the user console 110. The connections between the surgicalrobot 120, the user console 110, and the control tower 130 may be viawired and/or wireless connections and may be proprietary and/orperformed using any of a variety of data communication protocols. Anywired connections may be optionally built into the floor and/or walls orceiling of the operating room. The surgical robotic system 100 mayprovide video output to one or more displays, including displays withinthe operating room, as well as remote displays accessible via theInternet or other networks. The video output or feed may also beencrypted to ensure privacy and all or portions of the video output maybe saved to a server or electronic healthcare record system.

Prior to initiating surgery with the surgical robotic system, thesurgical team can perform preoperative setup. During the preoperativesetup, the main components of the surgical robotic system (e.g., table124 and robotic arms 122, control tower 130, and user console 110) arepositioned in the operating room, connected, and powered on. The table124 and robotic arms 122 may be in a fully-stowed configuration with thearms 122 under the table 124 for storage and/or transportation purposes.The surgical team can extend the arms 122 from their stowed position forsterile draping. After draping, the arms 122 can be partially retracteduntil needed for use. A number of conventional laparoscopic steps mayneed to be performed including cannula placement and insufflation. Forexample, each sleeve can be inserted with the aid of an obturator, intoa small incision and through the body wall. The sleeve and obturatorallow optical entry for visualization of tissue layers during insertionto minimize risk of injury during placement. The endoscope is typicallyplaced first to provide hand-held camera visualization for placement ofother cannulas. After insufflation, if required, manual instruments canbe inserted through the sleeve to perform any laparoscopic steps byhand.

Next, the surgical team may position the robotic arms 122 over thepatient and attach each arm 122 to a corresponding sleeve (e.g.,cannula). The surgical robotic system 100 has the capability to uniquelyidentify each tool (endoscope and surgical instruments) upon attachmentand display the tool type and arm location on the open or immersivedisplay 118 at the user console 110 and the touchscreen display on thecontrol tower 130. The corresponding tool functions are enabled and canbe activated using the master UIDs 116 and foot pedals 114. Thepatient-side assistant can attach and detach the tools, as required,throughout the procedure. The surgeon seated at the user console 110 canbegin to perform surgery as teleoperation using the tools controlled bytwo master UIDs 116 and foot pedals 114. The system translates thesurgeon's hand, wrist, and finger movements through the master UIDs 116into precise real-time movements of the surgical tools. Therefore indirect teleoperation, the system constantly monitors every surgicalmaneuver of the surgeon and pauses instrument movement if the system isunable to precisely mirror the surgeon's hand motions. In case theendoscope is moved from one arm to another during surgery, the systemcan adjust the master UIDs 116 for instrument alignment and continueinstrument control and motion. The foot pedals 114 may be used toactivate various system modes, such as endoscope control and variousinstrument functions including monopolar and bipolar cautery, withoutinvolving surgeon's hands removed from the master UIDs 116.

FIG. 2 is a schematic diagram illustrating one exemplary design of arobotic manipulator, a tool drive, and a connector loaded with a roboticsurgical tool, in accordance with aspects of the subject technology. Asshown in FIG. 2, the example surgical robotic manipulator 122 mayinclude a plurality of links (e.g., a link 202) and a plurality ofactuated joint modules (e.g., a joint 204, see also joints J1-8) foractuating the plurality of links relative to one another. The jointmodules may include various types, such as a pitch joint or a rolljoint, which may substantially constrain the movement of the adjacentlinks around certain axes relative to others. Also shown in theexemplary design of FIG. 2 is a tool drive 210 attached to the distalend of the robotic arm 122. The tool drive 210 may include a cannula 214coupled to its end to receive and guide a surgical instrument or endeffector 220 (e.g., endoscopes, staplers, scalpel, scissors, clamp,retractor, etc.). The surgical instrument (or “tool”) 220 may include anend effector 222 at the distal end of the tool. The plurality of thejoint modules of the robotic manipulator 122 can be actuated to positionand orient the tool drive 210, which actuates the end effector 222 forrobotic surgeries. The end effector 222 is at a tool shaft end. In otherembodiments, the tool shaft end is a tip of a needle or other object.

In the example of FIG. 2, the joint J0 is a table pivot joint andresides under the surgical table top. Joint J0 is nominally held inplace during surgery. Joints J1 to J5 form a setup or Cartesian arm andare nominally held in place during surgery, so do not contribute tomotion during surgical teleoperation. Joints J6 and J7 form a sphericalarm that may actively move during surgery or teleoperation. Joint J8translates the tool 220, such as the end effector 222, as part of a tooldriver. Joint J8 may actively move during surgery. Joints J6-8 activelyposition a tool shaft end (i.e., end effector 222) during surgery whilemaintaining an entry point into the patient at a fixed or stablelocation (i.e., RCM) to avoid stress on the skin of the patient. Duringset-up, any of the joints J0-J8 may move. During surgery, the jointsJ6-8 may move subject to hardware or safety limitations on position,velocity, acceleration, and/or torque. The surgical tool 220 may includenone, one, or more (e.g., three) joints, such as a joint for toolrotation plus any number of additional joints (e.g., wrists, rotationabout a longitudinal axis, or other type of motion). Any number ofdegrees of freedom may be provided, such as the three degrees from thejoints J6-8 and none, one, or more degrees from the surgical tool 220.

FIG. 3 is a flow chart diagram of one embodiment of a method for remotecenter of motion control of a surgical robotic system. The workspace ofthe end effector 222 of the surgical instrument 220 is aligned with thetarget anatomy in a way considering the various options for positioningof the robotic arm 122. The alignment may account for repositioning ofthe RCM during teleoperation. The RCM may be repositioned based on forcesensing, such as sensing using sensors in the adaptor of the roboticmanipulator for connecting with the cannula 214.

The method of FIG. 3 is implemented by a control processor, such as thecontrol tower 130, computer, workstation, sever, or another processor.Any computer of the surgical robotic system 100 may be used. A userinterface provides the movement commands from the user received in act300. The control processor (e.g., controller) establishes the RCM in act310, determines the overlap in act 330, and selects joint position inact 340. A force sensor, such as a torque or pressure sensor, sensesforce in act 320. The robotic arm 122 and/or surgical tool 220 are movedusing the instructions or control from the control processor in act 350.Other devices may perform and/or be used in any of the acts.

The acts are performed in the order shown or other orders. For example,act 300 is performed after any of the other acts. As another example,act 320 is performed before or after any of the acts.

Additional, different, or fewer acts may be used. For example, act 300is not provided where the alignment is performed prior to teleoperation.As another example, act 320 is not performed, such as where workspacealignment is performed without dynamic change in the RCM (e.g.,alignment prior to teleoperation and/or movement by the patient). Inanother example, acts 330 and 340 are not provided where force sensingon the adaptor is used to control RCM without considering workspacealignment. In another example, acts for initially positioning thesurgical tool 220 in the patient, planning surgery, and/or removing thesurgical tool 220 from the patient may be provided.

In act 300, the control processor receives a user command to move therobotic manipulator 122 or surgical tool 220 of the robotic manipulator122 prior to or during the teleoperation on a patient. The user input isreceived from the user console 110, such as the pedals 114 or userinterface devices 116, via wireless or wired interface by the controlprocessor. In other embodiments, the user commands are received byloading from memory or transmission over a computer network.

In preparation for teleoperation, the user sits down at the surgeonconsole 110. After positioning of the robotic manipulator 122 forteleoperation, one or more joints are locked in place with a RCM at thepatient skin or incision entry point. For example, joints J0-J5 (seeFIG. 2) are locked. The locking is by a brake and/or avoiding energizingthe motors for the joints. These joints remain locked duringteleoperation. Any of joints J0-J5 may be unlocked and moved to changethe RCM.

During teleoperation, the user enters commands to move the roboticmanipulator 122 and/or surgical tool 220. The commands are for motion.Different commands may be provided for different movements. The commandsmay be for movement of the end effector 222. These commands may not befor movement of particular joints. The control processor converts themovement commands to controls of particular joints of the roboticmanipulator 122 and/or surgical tool 220.

In act 310, the control processor establishes the RCM for the roboticmanipulator 122. While preparing for the surgery, a table-side assistantinserts the cannula 214 through the patient's abdomen wall. The robotmanipulator 122 is docked to the cannula 214. An adaptor of the roboticmanipulator 122 connects to the cannula 214. Docking is carefullyperformed to avoid excessive force exertion on the abdomen ports. Afterthe robot manipulators 122 are docked, the RCM is set at the point ofinsertion. The spatial relationship of the adaptor in the roboticmanipulator frame of reference to the cannula 214 is known. Uponconnection of the adaptor to the cannula 214, the RCM at the point ofinsertion along the cannula 214 is set as the RCM.

The surgical robot 120 will perform the operation while maintaining theRCM at the fixed position. Without motion of the RCM, the roboticmanipulator 122 continues to operate with the RCM in one location andwithout risk of harm to the tissue of the patient.

Due to patient motion, motion of the robotic manipulator, and/or anothersource of motion, the RCM may be moved. During the operation, theabdomen position may change for various reasons. The operation mayinvolve several phases where the patient may be positioned and orienteddifferently by adjusting the height and inclination of the table.Because the relative positions of the abdomen openings may be shifting,maintaining a fixed RCM position could introduce additional stress onthe patient's abdomen and may lead to unnecessary trauma or injuries.The robotic manipulator 122 accounts for the shift or motion by movingthe RCM to avoid harm to the tissue of the patient.

The RCM is established at a new location in the coordinate system of therobotic manipulator 122. To avoid having to release and redock therobotic arm 122 from the cannula 214, the RCM shifts or changes based ona measured force at the RCM (i.e., at the insertion location into thepatient). A force, such as a pressure or torque, is measured at or forthe RCM in act 320. The force is measured in any number of degrees offreedom, such as measuring force in two degrees of freedom along a planetangential to the patient at the insertion point or measuring in sixdegrees of freedom to account for three translational and threerotational forces (or torques). The force at the RCM after dockingand/or during teleoperation by the robotic manipulator 122 and thesurgical instrument 220 is sensed. The force sensing may enable therobotic system 120 to issue warnings and to assist RCM adjustments tominimize stress or force on the patient's abdomen. The force sensing maybe used for automatic adjustment of the RCM. The feedback from act 320to act 310 shows using the force to reposition the RCM.

In one embodiment, the force is sensed in act 320 with one or moresensors on the cannula 214. FIG. 6 shows a force sensor 600 for sensingforce of the cannula 214 (e.g., trocar) on the patient tissue. Since thecannula 214 connects to the robotic manipulator 122 after docking,relative motion between the patient and the robotic manipulator 122causes force on the cannula 214 by the patient tissue. The presence ofinjurious forces at the insertion port can be checked by integrating thesensor 600 onto the cannula shaft to measure strain at the incisionsite.

The sensor 600 is a force gauge, such as a thin capacitive or resistivesensor. Due to a thin and flexible structure, the sensor 600 may bewrapped around the cannula shaft. Once docked to the robotic manipulator122, the electrical connection of the control processor to the sensor600 is stablished through the docking site (i.e., adaptor) so that theforce sensor is turned on. Other connections, such as wirelessconnection or cabled connection, may be used. The readings of the sensor600 provide a direct measure (e.g., continuous real-time monitoring) offorce magnitude and/or direction at the tool insertion site. If themagnitude of forces sensed by the integrated sensor 600 exceeds apredefined safety threshold (e.g., forces that may cause injury), adesired RCM motion is computed to shift the RCM, rather than keeping theRCM fixed.

In another embodiment, the sensor 600 is in an adaptor 420 of therobotic manipulator 122. FIGS. 4A and 4B show an example. The adaptor420 is configured to connect the robotic manipulator 122 to the cannula214. For example, the adaptor 420 is a recess or female connector shapedto allow connection in a fixed orientation, such as a cuboid having atrapezoid shape. Other keyed shapes may be used. Alternatively, theadaptor 420 is a male connector formed as a keyed extension. A snap fit,pressure fit, motorized lock, and/or mechanical latch may be provided tolock the adaptor 420 to the cannula 214 for docking.

The forces (e.g., lateral force and/or torque) at the contacting pointson the cannula adapter 420 of the robotic manipulator 122 are measuredin act 320. Sensing at the adaptor 420 may avoid the design difficultiesand sterilization concerns of placing sensors 600 directly on thecannula 214.

The sensor 600 may be any type of sensors to correlate the force fromthe abdomen. For example, pressure, strain, force, or proximity sensorsmay be used. The sensor 600 may be formed from multiple sensors, such asusing a plurality of one-degree of freedom sensors. The sensor sensesforce in one direction or rotation. By using different sensors indifferent positions within or on the adaptor 420, forces in different,multiple degrees of freedom are measured. For example, pressure sensorsare positioned on five surfaces in the adaptor corresponding to the fivesurfaces forming the keyed shape. The surfaces of the adaptor 420 thatcontact the cannula 214 when connected each have a sensor. Fewer or moresensors may be provided.

In the example of FIGS. 4A and 4B, the pressure sensors are inside thedistal cannula adapter 420. The sensors are placed on the robotmanipulator 122 and underneath the sterile drape in order to minimizethe risk of contamination and potential damages to the sensors. As therobot manipulator 122 gets docked to the cannula 214 (see FIG. 4A), thesensor arrangement covers all possible directions of pressure originatedfrom the stress on the abdomen wall. Given the known spatialrelationship of the adaptor 420 to the cannula 214, the sensed forces atthe adaptor 420 may be geometrically related to the force at theinsertion point (see FIG. 4B). The measurements from the sensors arecalibrated, based on the type and geometry of the cannula 214, toeliminate the nominal pressure from the docking mechanism and tocorrelate the additional pressure readings to the forces on the abdomenwall.

Diagrams of the force direction and magnitude may be displayed to theuser. Robotic manipulator 122 adjustment may be performed automatically,semi-automatically, or manually by the user to minimize the force on theabdomen. In cases when the forces rise above a safety threshold,warnings may be issued to the user.

Referring again to FIG. 3, in act 330, the control processor determinesan amount of overlap between a target anatomy and each of a plurality ofworkspaces of the surgical instrument 220 on the robotic manipulator122. The robotic manipulator 122 and/or surgical instrument 220 may beconfigured (i.e., the joint angles set) in various possible ways. Forexample, at the RCM, the joint J6, a spherical roll joint, may havevarious positions discretized over any range and any number of stepswithin the range. At each possible position, a workspace volume isprovided for the end effector 222 or the surgical instrument 220. Therobotic manipulator 122 and surgical instrument 220 may be moved andoperate within the particular workspace volume. Each position of thejoint J6 or other robot configuration provides the workspace at adifferent relative location (e.g., different translated and/or rotated).

Based on the configuration of the robotic manipulator 122, the controlprocessor computes the accessible workspace of the end effector 222. Forexample, the workspace is a sphere around the RCM point with someunreachable conical cuts inside. FIGS. 5 and 6 shows the workspace as ashaded sphere with a conical region which the end effector 222 cannotreach. If the origin of the J6 joint (spherical roll) is translated bykeeping the RCM fixed, the workspace will rotate about its center. Theconical region rotates to different positions relative to the patient.If the RCM is moved, then the workspace will shift in space as well.

For workspace alignment, the target anatomy is determined in thecoordinate system of the robotic manipulator 122. The surgeon manually,or the imaging system automatically, defines the boundaries of thetarget anatomy. Intraoperative or pre-operative imaging may be used tosegment the region of interest for the teleoperation, such asidentifying an organ, lesion, or part of anatomy. X-ray, computedtomography, ultrasound, or magnetic resonance imaging may be used. Inanother embodiment, an endoscopic view and the surgeon's knowledge ofhuman anatomy are used.

Using calibration, an imaging detector mounted at a known spatiallocation relative to the robotic manipulator 122 (e.g., imaging withendoscope on a robotic manipulator 122), and/or detection of part of therobotic manipulator 122 or surgical instrument 220 in the imaging, thecoordinate systems for the imaging and the robotic surgical system 120are aligned or registered. The target anatomy may be located in thecoordinate system of the robotic manipulator 122.

The overlap of the volume or other region of the target anatomy with theworkspace is optimized. Various workspaces are possible, correspondingto different positions of the robotic manipulator 122 about the RCM.Before or during teleoperation, after the robotic manipulator 122 isdocked, optimal joint angles may be computed to maximize the volumetricoverlap of the surgical tool's workspace and the target organ/tissuewhile holding RCM point fixed (i.e., constrained optimization). Thepossible workspaces in the example using joint J6 have differentorientation of the workspace (no translation) so that the unreachablezones (the conical cuts in the workspace) are maintained outside of thetarget tissue/organ to a maximum extent.

The amount of overlap of the possible workspaces (i.e., workspaceoriented over the range of configurations) with the volume of the targetanatomy is determined. The volume, area, and/or distance of the spatialoverlap of the workspace and the target anatomy is calculated. Theamount of overlap may be different for different possibleconfigurations, such as different orientations over the discretizedrange of joint positions for a spherical roll joint. Due to differentpossible configurations, the workspace may be translated and/or rotatedwhile maintaining the RCM.

The different possible workspace orientations and/or positions aresearched to find the greatest amount of overlap. The amount of overlapfor each possible workspace with the target anatomy is determined. Afterthe robotic manipulator 122 is docked to the cannula 214, the controlprocessor scans or searches through a discretized neighborhood of theconfigurations (e.g., J6 (spherical roll) joint positions) and computesthe overlapping volumes of the workspace corresponding to eachconfiguration (e.g., movement of J6 origin within the specifiedneighborhood) with the target anatomy. The configuration that providesthe maximum overlap is selected as the “optimal configuration.”

Rather than searching all possible workspaces, a non-linear search maybe used. Instead of the linear search, nonlinear optimization methods,such as simulated annealing or a coarse-to-fine search, may be used tospeed up the search. In order to obtain the optimal pose quickly, thesearch may be done locally, assuming that the initial manipulatorconfiguration is already close to an optimum. This may lead to a searchresult that may suggest “fine-tuning” of the manipulator configurationrather than a gross-repositioning.

The determination of the configuration to maximize overlap is performedonce the RCM is established (e.g., after docking). This determinationmay occur prior to teleoperation. The determination may be repeated. Thedetermination may occur for each change in the RCM during teleoperation.The determination may occur as the target anatomy shifts, such asthrough staged operation on different anatomy. The determination mayoccur due to a change in the surgical tool 220 or for any other reasonwhere the target anatomy or workspace shifts or changes.

In act 340, the control processor selects the position of the roboticmanipulator with a greatest of the amount of overlap. The configurationfor the possible workspace that provides the most overlap with thetarget anatomy is selected. FIG. 5 shows an example. The workspaceorientation on the left shows part of the target anatomy being outsidethe workspace sphere, such as in the conical cut-out. The workspaceorientation on the right shows the workspace sphere rotated so that noneof the target anatomy is outside of the workspace (i.e., conical cut-outis rotated to not intersect the target anatomy). The configuration ofthe robotic manipulator 122 (e.g., rotation angle of joint J6) isselected to provide the greatest overlap.

Such selection is repeated during teleoperation. The same or differentconfiguration is selected for each repetition. Due to positional shifts,more or less maximum overlap may be provided. Due to positional shifts,a different configuration may provide greater overlap than the previousconfiguration providing greatest overlap. A different one of thepossible workspaces and corresponding configuration is selected.

In act 350, the control processor moves the robotic manipulator 122 tothe selected position or configuration. The control processor causesmovement of the robotic manipulator 122 and/or the surgical tool 220.The output movement commands for the active joints for docking and/orduring teleoperation cause the joints to change position. The roboticmanipulator 122 is moved to be in the selected configuration.

In one example using the joint J6, the selection of act 340 provides atarget x and y movement of the joint J6 (spherical roll, sr) origin,which target provides the optimal pose (i.e., maximum overlap of therobot workspace and the target anatomy): w_(x,sr), w_(y,sr). The roboticmanipulator 122 is moved to this optimal configuration (q_(opt)) whilekeeping the forces (and therefore strain) at the RCM at a safe level. Ifthe robotic manipulator 122 was docked without pulling/pushing thecannula 214 and if the patient remains stationary, then a special caseoccurs where the force at the insertion port is small (thus safe) fromthe beginning, and the RCM is maintained fixed at this location. In casethere are residual forces acting on the cannulas 214 after dockingand/or due to another source, the strain is relieved by updating (i.e.,sliding) the RCM position as well as optimizing the overlap.

The joint position or robotic manipulator 122 configuration may beselected in act 340 based on more than overlap. The selection may bebased on the user commands in teleoperation, an adjustment of the RCM toreduce the force, and/or an amount of overlap of a workspace of thesurgical instrument 220 with a region of interest in the patient (i.e.,target anatomy). The configuration is selected in a way accounting forvarious concerns.

In one embodiment that accounts for possible RCM repositioning andoverlap optimization with or without teleoperation commands, thereadings of the sensor 600 provide a direct measure (e.g., continuousreal-time monitoring) of force magnitude and direction at the toolinsertion site for repositioning the RCM. If the magnitude of forcessensed exceed a predefined safety threshold (e.g., forces that may causeinjury), a desired RCM motion is computed based on the magnitude, ratherthan keeping the RCM fixed. One example of this control is provided by:

${if}{\mspace{11mu}\;}\left( {{{{norm}\mspace{14mu}\left( {\overset{\rightarrow}{F}}_{sensed} \right)} > \left( {\overset{\rightarrow}{F}}_{threshold} \right)},{{{then}\mspace{14mu}{\overset{\rightarrow}{\Delta\; p}}_{RCM}} = {{\,_{J\; 7}^{base}R}*{\,_{sensor}^{J\; 7}R}\frac{\left( {{\overset{\rightarrow}{F}}_{sensed} - {\overset{\rightarrow}{F}}_{threshold}} \right)}{K}}},{{{else}\mspace{14mu}{\overset{\rightarrow}{\Delta\; p}}_{RCM}} = \overset{\rightarrow}{0}}} \right.$

where {right arrow over (F)}_(sensed) is the sensed force vector, {rightarrow over (F)}_(threshold) is the threshold force vector, {right arrowover (Δp)}_(RCM) is the change in position vector of the RCM, _(J7)^(base)R is the 3×3 rotation matrix from robot base (world frame) tojoint J7 (spherical pitch) frame, and _(sensor) ^(J7)R is the 3×3rotation matrix from the joint J7 frame to the sensor's coordinateframe. The rotation matrix may dynamically change depending on theconfiguration of the robotic manipulator 122. _(sensor) ^(J7)R is afixed registration since once the manipulator is docked, the orientationof the cannula 214 is fixed relative to the distal block attached to J7.K is a spring stiffness that defines how much translation is to becommanded to the robot to relieve a given force. A large K value lead toa “not-so-responsive” system. A small K value will generate a sensitivesystem trying to drop the force to the set safety threshold quickly. Ifthe sensitive system is not well-tuned, overshooting, and thusoscillatory robot motion, may result.

FIG. 6 shows an example of both workspace alignment and shift in RCM forselection of the robot configuration for the robotic manipulator 220 ofFIG. 2. During teleoperation, there may be excessive forces at thecannula 214, such as due to motion of the patient. To avoid injuries,the detected force F on the cannula 214 (sensed via embedded forcesensors 600) is used to compute a new RCM position, {right arrow over(Δp)}_(RCM), to relieve injurious stress at the insertion port. Theoptimal joint angles are recomputed under this new RCM constraint toreorient the workspace such that the target/tissue is still maintainedto the maximum extent within the reachable workspace. The roboticmanipulator 122 is moved by moving one or more joints according theoverlap and the RCM repositioning with or without movement of thesurgical instrument from an operator during teleoperation. The proximalwrist (J11), distal wrist (J10) and tool rotate joints (J9) of thesurgical instrument 220 are not used if repositioning beforeteleoperation. In teleoperation, these joints (J9, J10 and J11) receivecommands only for tool manipulation. For the spherical manipulatorjoints (J6, J7, J8), the computed incremental joint commands for overlapand RCM position are added to the command due to teleoperation of thesurgeon so that the repositioning can take place continuously (evenduring the teleoperation).

The incremental joint movements to satisfy both the workspacerequirement, i.e., the incremental movement of the spherical roll jointorigin about the RCM point (w_(x,sr), w_(y,sr)), and the insertion portforce requirement (i.e., the displacement of the RCM point to relievethe excess force at the RCM ({right arrow over (Δp)}_(RCM))) may becomputed sequentially (e.g., reposition RCM, then optimize for overlapgiven the configuration possibilities at the new RCM position).Alternatively, the various motions can be used in one solution, such asgiven by:

$\left. {{J = \begin{bmatrix}\; & J_{tr} & \; \\J_{RCM} & \; & 0_{3 \times 3} \\J_{st} & \; & 0_{2 \times 3}\end{bmatrix}}{\overset{\rightarrow}{\Delta\; x} = {\begin{bmatrix}{\overset{\rightarrow}{\Delta\; p}}_{tr} \\\omega_{z,{tr}} \\{\overset{\rightarrow}{\Delta\; p}}_{RCM} \\\omega_{x,{sr}} \\\omega_{y,{sr}}\end{bmatrix} = \begin{bmatrix}{\overset{\rightarrow}{\Delta\; p}}_{RCM} \\0 \\{\overset{\rightarrow}{\Delta\; p}}_{RCM} \\\omega_{x,{sr}} \\\omega_{y,{sr}}\end{bmatrix}}}{{\overset{\rightarrow}{\Delta\; q}}_{repo} =}} \right\rbrack^{+}*\overset{\rightarrow}{{\Delta\; x}\;}$

where ] denotes a combined Jacobian, ]⁺ is the pseudoinverse of thiscombined Jacobian, x, y, z are spatial coordinates, tr is tool roll (J9)joint origin, and sr is spherical roll (J6) joint origin. The resulting{right arrow over (Δq)}_(repo) is a 9×1 vector and contains theincremental joint command for joints J1-J9 due to repositioning. JointsJ10 and J11 (proximal wrist and distal wrist on the surgical instrument220) are not involved in this motion. When joints J6-J11 receiveadditional commands due to teleoperation ({right arrow over(Δq)}_(teleop)), the two commands ({right arrow over (Δq)}_(teleop) and{right arrow over (Δq)}_(repo)) are summed up to satisfy (1) workspacerequirement, (2) insertion-port force requirement, and (3) teleoperationcommands at the same time. J1-J5 are not involved in performing theteleoperation commands, so their rows are shown as zeros in {right arrowover (Δq)}_(teleop). The resulting joint command vector for the entirerobot (J1-J11) is given by:

$\overset{\rightarrow}{\Delta\; q} = {\begin{bmatrix}{\overset{\rightarrow}{\Delta\; q}}_{repo} \\0 \\0\end{bmatrix} + \begin{bmatrix}0 \\0 \\0 \\0 \\{\overset{\rightarrow}{\Delta\; q}}_{teleop}\end{bmatrix}}$

Other command or control functions may be used. Other processes forsolving for the three sources of movement and positioning may be used.

The selection of the configuration based on workspace alignment, forcesensing for RCM change, and/or teleoperation is performed once or may berepeated. Where repeated (see feedback from act 350 to act 300), therobotic manipulator 122 is moved to the selected positions andcorresponding configurations over time.

Before starting teleoperation, the robotic surgical system 120 guidesthe operator to bring the robotic manipulator 122 to the computed“optimal” pose for workspace alignment given the RCM for docking. Theguiding is performed quickly and easily based on the computed jointmovements ({right arrow over (Δq)}).

The guidance may be performed in a number of different ways. In a hapticguidance via virtual fixtures, active (pseudo-automatic approach) orpassive virtual fixtures may be used. In the active approach, on top ofuser applied force, virtual spring forces are generated to pull therobotic manipulator 122 toward the optimal pose. In this scheme, themanipulator 122 automatically moves toward the optimal pose, but theuser can always override or resist the motion by applying counter-force.This allows the user to be kept in the control loop for safety. In thepassive approach, the robotic manipulator 122 is not moved automaticallybut is moved based on the components of the user applied force ortorque. The component of the user force or torque toward the optimalpose are amplified while the other components are scaled down. Thiscreates a totally user-driven motion but with a haptic feedback to theuser, sensing resistance if trying to move away from the target pose butsensing support if moving toward the optimal pose.

In another guidance, auditory feedback is used. The user is given audiosuggestions to bring each joint of the robot to their target position,such as “Rotate joint 1 clockwise.” If the target position is overshot,the audio command switches to “rotate joint 1 counterclockwise.”Meanwhile, the rest of the joints automatically align themselves tocomply with the RCM constraint or force requirement.

In yet another guidance, visual feedback is used. The user is guidedthrough virtual cues to adjust the position of each individual joint.For example, LED status lights on each joint are red if the joint needsto be adjusted. Once the joint reaches the computed position for the“optimal” overall pose, the LED turns green. As another example, anaugmented reality display guides the user with arrows superimposed on aview of the actual robot or user input controls.

After starting teleoperation, the same or different guides may be usedto adjust the configuration and move the robotic manipulator 122 basedon the repositioning of the RCM and/or workspace alignment.Alternatively, the configuration based on workspace alignment and/or RCMforce reduction is performed automatically with or without userconfirmation to initiate the change.

In an example use case, before starting teleoperation, after themanipulators are docked, the repositioning aid repositions or assists inrepositioning the RCM (e.g., pure translate of RCM) so that the stressbetween the patient and the cannula 214, if any is relieved. Therepositioning is also to adjust any one or more of joints J1-J9 in angleto rotate the workspace (i.e., no translation) so that the targetanatomy is fully or more in the robot's workspace.

After the teleoperation starts, the workspace requirements may stillchange, such as due to intraoperative complications, intra-operativelydiscovered anatomical variations, metastases, deformation or shifting oforgans during the surgery, etc. . . . . As a result, the new targetanatomy may fall out of or be less covered by the boundaries of thepreviously optimized workspace of the robotic manipulator 122. If suchchanges in the required anatomical workspace are sensible (e.g.,endoscope images combined with joint angles can tell where the surgeonis trying to reach and instrument joints reach their limits but thesurgeon is not being able to reach the anatomy to operate), the overallmanipulator pose may be continually or periodically reoriented so thatthe target anatomy is maintained within the reachable workspace of theinstrument 220. The reorienting may be triggered to occur, such as bythe user. The reorientation allows for continuous teleoperation withouthaving to stop, rethink the arrangement of the anatomy, workspace, andmanipulator, then manually bring the manipulators to a new pose, andfinally to continue operation. This may prevent loss of operative time.

During the surgery, there may be movement of the tissues as well as theentire patient abdomen. This may induce additional pulling forces on thecannula 214 and cause trauma at the insertion ports on the patient.Extended force application on the patient, like any excess sustainedcompression of tissues, leads to decreased perfusion of the tissue. Toomuch force applied to the tissue may impede the capillary blood flow inthe skin and also disrupt perforating fascial vessels to the skin. Thisdecreased oxygen delivery to the tissues can be a contributor toincision site hernias and wound-healing complications. Therefore, duringthe operation, excessive forces at the incision site are prevented orlimited by re-adjusting the overall manipulator pose. The forces on thecannula 214 are sensed, and the sensed forces are used as a feedbackmechanism for use in the assisted, automatic, or guided repositioningcontrol mode to re-configure the manipulator pose so that the forces atthe cannula site are maintained at a tissue-preserving level throughoutthe surgery.

FIG. 7 shows a block diagram of one embodiment of a surgical roboticsystem for medical teleoperation. The system performs the method of FIG.3 or another method. Any one or more (e.g., all) of workspace alignmentor force sensing to reposition RCM may be used.

The surgical robot system includes one or more robot manipulators 122with corresponding surgical instruments 220 or other types ofinstruments connected with the robotic manipulators 122, a controller702, and a memory 704. The user console 110 is represented or includedas part of the surgical robot system. Additional, different, or fewercomponents may be provided. For example, the robotic manipulator 122,surgical instrument 220, and/or user console 110 are not provided.

The robotic manipulators 122 each include one or more links and joints.The joints may be pitch or roll joints. A tool drive and cannula 214 forreceiving and guiding a surgical tool may be provided on each of therobotic manipulators 122. Different combinations of links and joints maydefine or form different parts of the robotic manipulators 122, such asdifferent parts having different degrees or types of movement (e.g.,translation and/or rotation). Any now known or later develop roboticmanipulator 122 with motors, sensors, links, joints, controllers,surgical instruments, and/or other structure may be used.

One or more robotic manipulators 122 are provided. For example, three orfour robotic manipulators 122 are provided. The robotic manipulators 122mount to a table, such as a base of an operating table. Alternatively,cart, floor, ceiling, or other mounts may be used. The roboticmanipulators 122 include a cable or wireless transceiver forcommunication with the controller 702 or an intermediary (e.g., controltower 130).

The robotic surgical instruments 220 are one or more graspers,retractors, scalpels, endoscopes, staplers, scissors, or other surgicaldevice for manipulating tissue of the patient. The tissue manipulationmay be direct, such as cutting or grasping. The tissue manipulation maybe indirect, such as an endoscope pressing or contacting tissue asguided to image or view an interior portion of the patient. Different orthe same type of instruments 220 may be mounted to different ones of therobotic manipulators 122. For example, two robotic manipulators 122 mayhave graspers, a third robotic manipulator 122 may have a scalpel, and afourth robot manipulator 122 may have an endoscope.

The robotic surgical instruments 220 connect to the distal ends of therobotic manipulators 122 but may connect at other locations. Theconnection provides a drive so that the tool may be operated, such asclosing a grasper or scissors.

The robotic manipulator 122 includes a connected adaptor 420 configuredfor connecting with the cannula 214 for docking and teleoperation. Thisconnection with the cannula 214 positions the surgical instrument 220 topass through the cannula 214 at the insertion point for access to theinterior of the patient. The insertion point is established as an RCMfor the robotic manipulator 122 and surgical instrument 220.

One or more sensors 600 on the cannula and/or on the adaptor 420 monitorthe tissue stress for repositioning the RCM. For example, pressuresensors are on different surfaces of the adaptor 420. The differentsurfaces are ones that contact the cannula 214 when connected. Thepressure sensors of the different surfaces of the recess or projectionof the adaptor 420 sense one or more degrees of freedom. In combination,a vector of forces is sensed.

The user console 110 is a graphics user interface for interaction of thesurgeon with the surgical robot system, such as with a processor forcontrolling the robotic manipulators 122. The user interface includes auser input 708 and a display 118. The user input 708 and/or the display118 are provided at the user console 110 and/or control tower 130 butmay be at other locations.

The user input 708 is a button, a keyboard, a rocker, a joy stick, atrackball, a voice recognition circuit, a mouse, a touch pad, a touchscreen, sliders, switches, UID 116, foot pedal 114, combinationsthereof, or any other input device for inputting to the surgical robot.The display 118 is a monitor, liquid crystal display (LCD), projector,plasma display, CRT, printer, or other now known or later developeddevice for outputting visual information. In an alternative embodiment,the display 118 is a head mounted display. The user input 708 may be asensor or sensors for detecting eye movement and/or blinking. In yetother embodiments, the user input 708 is a microphone for voice-basedinput. A speaker for output of audio information may be provided insteadof or in addition to the display 118.

The optional camera 706 is a digital camera for optical tracking of usermotion, such as tracking during use of the UID 116 to control therobotic manipulator 122. The camera 706 may be a stereo camera and/ordepth camera in some embodiments. The camera 706 is positioned relativeto a user and a target pattern or user console 110 for tracking humanmotion in tracing the target pattern or controlling the roboticmanipulator 122 with the user input 708.

The controller 702 is a controller that drives and/or models the roboticmanipulators 122 and/or surgical instruments 220. The controller 702 isa general processor, central processing unit, control processor,graphics processor, graphics processing unit, digital signal processor,application specific integrated circuit, field programmable gate array,digital circuit, analog circuit, artificial intelligence processor,combinations thereof, or other now known or later developed device forcontrolling movement of the robot manipulator 122 and/or surgicalinstrument 220. The controller 702 is a single device or multipledevices operating in serial, parallel, or separately. The controller 702may be a main processor of a computer, such as a laptop, server,workstation, or desktop computer, or may be a processor for handlingsome tasks in a larger system. Based on hardware, software, firmware, orcombinations thereof, the controller 702 is configured to implementinstructions or perform acts.

The controller 702 is configured to adjust the RCM of the roboticmanipulator based on output from the sensor 600. The force at theinsertion point, as measured by the sensor 600 (e.g., multiple sensorson adaptor surfaces), is used to alter the RCM to relieve tissue stress.

The controller 702 is configured to determine an amount of overlapbetween a target anatomy and each of a plurality of workspaces of thesurgical instrument. The different workspaces correspond to differentpositions of the robotic manipulator 122 about the RCM. For a given RCM,different workspaces may be provided by the robotic manipulator 122having different configurations, such as workspaces with differentorientation due to rotation of a joint. The controller 702 is configuredto select the position of the robotic manipulator 122 (i.e., select theconfiguration) with a greatest of the amount of overlap of the workspacewith the target anatomy. The controller 702 is configured to move therobotic manipulator to the selected position, such as providing guidanceto move the robotic manipulator 122 to the desired configuration. Thisguidance and corresponding movement may be provided before and/or duringteleoperation, such as moving the robotic manipulator 122 to reconfigurefor workspace alignment in combination (superposition) with movement forsurgical manipulation of the patient by the surgical instrument 220.

The memory 704 or another memory is a non-transitory computer readablestorage medium storing data representing instructions executable by theprogrammed controller 702. The instructions for implementing theprocesses, methods and/or techniques discussed herein are provided oncomputer-readable storage media or memories, such as a cache, buffer,RAM, removable media, hard drive or other computer readable storagemedia. Computer readable storage media include various types of volatileand nonvolatile storage media. The functions, acts or tasks illustratedin the figures or described herein are executed in response to one ormore sets of instructions stored in or on computer readable storagemedia. The functions, acts or tasks are independent of the particulartype of instructions set, storage media, processor or processingstrategy and may be performed by software, hardware, integratedcircuits, firmware, micro code and the like, operating alone, or incombination. Likewise, processing strategies may includemultiprocessing, multitasking, parallel processing, and the like.

In one embodiment, the instructions are stored on a removable mediadevice for reading by local or remote systems. In other embodiments, theinstructions are stored in a remote location for transfer through acomputer network or over telephone lines. In yet other embodiments, theinstructions are stored within a given computer, CPU, GPU, or system.

While the invention has been described above by reference to variousembodiments, it should be understood that many changes and modificationscan be made without departing from the scope of the invention. It istherefore intended that the foregoing detailed description be regardedas illustrative rather than limiting, and that it be understood that itis the following claims, including all equivalents, that are intended todefine the spirit and scope of this invention.

I (we) claim:
 1. A method for remote center of motion control of asurgical robotic system, the method comprising: establishing a remotecenter of motion for a robotic manipulator; determining an amount ofoverlap between a target anatomy and each of a plurality of workspacesof a surgical instrument on the robotic manipulator, the workspacescorresponding to different configurations of the robotic manipulatorabout the remote center of motion; selecting the configuration of therobotic manipulator with a greatest of the amount of overlap; and movingone or more joints of the robotic manipulator to the selectedconfiguration.
 2. The method of claim 1 wherein establishing the remotecenter of motion comprises docking the robotic manipulator to a cannulaat an insertion location in a patient, the remote center of motion beingthe insertion location.
 3. The method of claim 1 further comprisingsensing a force at the remote center of motion during teleoperation bythe robotic manipulator and the surgical instrument; and whereinestablishing comprises establishing the remote center of motion from achange based on the force.
 4. The method of claim 3 wherein sensingcomprises sensing with a sensor on a cannula connected to the roboticmanipulator.
 5. The method of claim 3 wherein sensing comprises sensingwith a force sensor in an adaptor of the robotic manipulator, theadaptor configured to connect the robotic manipulator to a cannula. 6.The method of claim 5 wherein sensing comprises sensing with multipleone-degree of freedom sensors including the force sensor, the one-degreeof freedom sensors being on different surfaces of the adaptor, thesurfaces contacting the cannula when connected to the roboticmanipulator.
 7. The method of claim 3 wherein determining comprisesdetermining during the teleoperation, wherein selecting comprisesselecting during the teleoperation, and wherein moving comprises movingone or more joints of the robotic manipulator to account for theselected configuration and the remote center of motion established inresponse to the force.
 8. The method of claim 7 wherein moving comprisesmoving the one or more joints to account for the selected configuration,for the remote center of motion established in response to the force,and for movement of the surgical instrument from an operator during theteleoperation.
 9. The method of claim 1 wherein determining comprisesdetermining with each of the workspaces corresponding to discretizedrange of joint positions for a spherical roll joint.
 10. The method ofclaim 1 wherein determining the amount comprises determining the amountas a volume of overlap where the target anatomy is a segmented volumefrom medical imaging.
 11. The method of claim 1 wherein determiningcomprises searching the plurality of workspaces in a non-linear search.12. The method of claim 1 wherein determining and selecting are repeatedmultiple times during teleoperation, wherein selecting for differentones of the repetitions comprises selecting different ones of theworkspaces, and wherein moving comprises moving the robotic manipulatorto the selected positions over the repetitions.
 13. A method for remotecenter of motion control of a surgical robotic system, the methodcomprising: sensing a force at a remote center of motion of a roboticmanipulator; and adjusting a joint position of the robotic manipulator,the adjusting reducing the force at the remote center of motion andaccounting for an amount of overlap of a workspace of the surgicalinstrument with a region of interest in the patient.
 14. The method ofclaim 13 wherein sensing the force comprises sensing with a force sensoron a cannula connected with the robotic manipulator.
 15. The method ofclaim 13 wherein sensing the force comprises sensing with a plurality ofpressure sensors on different surfaces of an adaptor of the roboticmanipulator, the surfaces contacting a cannula.
 16. The method of claim13 wherein adjusting comprises searching different possible workspacesof the surgical instrument for a greatest of the amount of overlap withthe region of interest, the possible workspaces corresponding todifferent possible joint positions of the joint, and selecting thepossible workspace with the greatest amount of overlap.
 17. A surgicalrobotic system for medical teleoperation, the surgical robotic systemcomprising: a robotic manipulator; a surgical instrument connected tothe robotic manipulator; an adaptor connected to the roboticmanipulator, the adaptor configured to connect with a cannula duringteleoperation; a first sensor on the adaptor; and a controllerconfigured to adjust a remote center of motion of the roboticmanipulator based on output from the first sensor.
 18. The surgicalrobotic system of claim 17, wherein the adaptor has a plurality ofdifferent surfaces for contact with the cannula, the different surfacesforming a recess in the adaptor, wherein the first sensor is aone-degree-of-freedom sensor on a first of the different surfaces,further comprising a second sensor on a second of the differentsurfaces, wherein the controller is configured to adjust based outputfrom the first and second sensors.
 19. The surgical robotic system ofclaim 17 wherein the controller is configured to determine an amount ofoverlap between a target anatomy and each of a plurality of workspacesof the surgical instrument, the workspaces corresponding to differentpositions of the robotic manipulator about the remote center of motion,to select the position of the robotic manipulator with a greatest of theamount of overlap, and to move the robotic manipulator to the selectedposition.
 20. The surgical robotic system of claim 19 wherein thecontroller is further configured to move the robotic manipulator to theselected position while providing for movement of the roboticmanipulator during teleoperation of the surgical instrument.